Fixed-Wing UAV Crashed 10 Seconds After Bungee Launch – Need Log Analysis

ArduPlane Plane 4.6
1

I need help analyzing my last flight test logs.

Vehicle Type: Fixed-wing UAV launched using bungee

The drone was launched successfully using a bungee launcher and initially after around 10 seconds of flight, the drone suddenly lost stability and crashed to the ground.
I have attached the .bin flight log for analysis.

Could someone please help review the logs and identify the possible cause of the crash?

Thank you.

logs.zip (765.8 KB)

2

I wouldn’t agree. The plane wasn’t so much flying, as being thrown into the air. It was never really in control. The plane basically pitch up and flipped over.

image
image1227×673 95.9 KB

The flight controller was commanding corrections to the servos but they seemed to have little effect. I would check:

  • Are the flight controls moving in the correct direction for stabilisation. Especially the V-tail. Those are easy to get backwards.
  • Verify that the centre of gravity is correct. Given the climb it could be too far aft.
3

Another log file, 7.bin, shows a successful flight without any crash. The other two .bin files also indicate crash flights. Please check the logs .
Thank you for your response.

https://drive.google.com/drive/u/0/folders/1Rs72xdjcFYh3MKie5Uxi1kuuolq0WYUk

4

I just looked at log 7.

Overall tuning is not good. There is instability in the roll, and the pitch performance is one to two seconds behind the desired angle.

As for the take-off, I think this one was more luck than anything else. The plane still pitched up to 40 degrees (25 higher than desired) at low speed. I am a little surprised that it didn’t stall.

Verify the C of G is correct.

Set

SERVO_AUTO_TRIM,1
SERVO2_TRIM,1425
SERVO3_TRIM,1550

This might help get things under control.

Then run autotune and get the control loop dialed in better.